In recent years, evidence from psychophysical, neuroimaging and neurophysiological studies has accumulated suggesting that basic visual perceptual and cognitive functions such as attention and working memory emerge from the reciprocal interaction of oculomotor signals and visual representations in cortex. Our previous work suggests that saccade-related signals involving the frontal eye field (FEF) contribute to the attentional selection of visual stimuli and to the attention-related filtering of visual signals in cortex. In the present proposal, we plan to further examine the influence of saccade-related signals on visual representations in a set of three complimentary aims. In the first aim, we will address an important implication of our previous studies, namely that the activity of FEF neurons is necessary and sufficient for driving spatial attention. We will test the role of FEF neurons and compare it directly to that of area LIP neurons, which are also believed to be critical for attention. This will be accomplished via pharmacologically induced activation and inactivation of neurons in one of the two areas (FEF or LIP) and a study of its effects on attentional performance and the attentional modulation of neurons in the other area (LIP or FEF). In the second aim, we will use voluntarily generated saccades to pursue the relationship between saccade target selection and neural correlates of attention in visual cortex. Specifically, we will study the influence of saccade preparation on neural correlates of bottom-up and feature-based attention in area V4. In the third aim, we will leverage our previous observation that electrical microstimulation of the FEF drives spatial attention to test for a possible role of the FEF in gating working memory. Specifically, we will test the effects of FEF microstimulation on visual working memory and its correlates in inferior temporal cortex. Together, these three aims will allow us to determine the extent to which saccade-related signals influence the filtering and maintenance of visual representations in cortex and the relevance of those influences to visual perception cognition, and visually guided behavior. The questions addressed by the proposed research are central to an understanding of the neural basis of visually guided behavior, and thus achieving those goals will have direct and important implications for the neural bases and the treatment of disorders of visuomotor integration, perception and cognition. Key examples of such disorders include attention-deficit hyperactivity disorder (ADHD) and dyslexia, both of which appear to include deficits in oculomotor control. The proposed research is particularly relevant to ADHD, which afflicts more than five percent of children in the U.S., making it one of the most common mental disorders to affect children. Thus an understanding of the neural basis of visual attention clearly has important implications for human health.